Graffiti threatens to blow up Irvine school

March 10, 2010 12:22:01 AM PST

IRVINE, Calif. --

There's a security concern at University High School in Irvine on Wednesday after threatening graffiti was found on campus. Police said a student found the graffiti in a text book on Monday and alerted a teacher. The principal says words like, "We'll blow this place up," and "Everyone will die" were scrawled in the book, along with Wednesday's date.

There is an increased police presence on the campus on Wednesday, but the principal says investigators have not yet found any evidence to legitimize that threat.